Cordless balanced window covering

ABSTRACT

Disclosed is a spring motor and control for use especially with window blinds. The motor comprises a storage drum having a first axis, an output drum mounted for rotation about a second axis parallel to and spaced from the first axis. A spring member is connected to and between the storage drum and the output drum to form a spring motor. The spring motor has laterally extending, spaced apart drum supports on opposite sides of the drums to support them for rotation. A coupled drive is connected to the storage and output drum whereby rotation of one of the drums in a first direction about its axis effects rotation of the other of the drums about its axis and in an opposite direction to cause winding and unwinding of the spring member between the drums. A drive actuator is connected to the coupled drive to effect rotation of the drums, and an adjustable friction member is engageable with one of the coupled drive and the drive actuator to adjustably alter the force necessary to effect movement of the coupled drive.

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of, and claimspriority from the following applications: (1) Provisional ApplicationSer. No. 60/126,410, filed on Mar. 26, 1999, and entitled “CordlessBalanced Window Covering”, (2) “Cordless Balanced Blind”; Ser. No.08/629,896; filed Apr. 10, 1996, which is continuation of (3) “CordlessBalanced Window Covering”; Ser. No. 08/303,773; Filed Sep. 9, 1994; nowU.S. Pat. No. 5,531,257, issued Jul. 2, 1996, which is acontinuation-in-part of (4) “Cordless, Balanced Venetian Blind or ShadeWith Consistent Variable Force Spring Motor” Ser. No. 08/223,989, FiledApr. 6, 1994; now U.S. Pat. No. 5,482,100, issued Jan, 9, 1996. Anotherrelated application is “Cellular Lift Cord and Weight AdjustmentMechanism”, Ser. No. 09/229,111, filed on Jan. 12, 1999, all owned bythe Assignee of the present invention.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the art of springmotors useful for a variety of applications, including venetian blindsand window shades. More specifically the present invention relates to asystem in which lifting cords and cord mechanisms are eliminated fromshades or blinds. More specifically the invention relates to windowcovering systems which, inter alia, employ one or more spring motors tobalance the weight of the accumulated window covering material,independent of the extent to which the blind or shade is raised orlowered. Even more specifically, the present invention utilizes anadjustable friction member for engagement with one of a coupled driveand drive actuator to permit the use of spring motors not requiring suchrigid specifications.

[0004] 2. Description of the Art

[0005] Venetian blinds have been known for many years and typicallyinclude a plurality of slats made from a variety of materials, such asmetal, wood, plastic or other materials and supported by ladders.

[0006] Such blinds typically include a bottom rail or bar and some kindof tilt mechanism to enable the slats to move from a horizontal positionto a nearly vertical position to open and close the blinds with respectto the passage of light. As is also conventional with such systems,flexible line members or lifting cords are coupled to the bottom rail,passing through the slats and into mechanisms within an upper headrail.The cords are employed to raise the bottom rail, accumulating individualslats as the bottom rail is raised. Because of gravity, the naturaltendency of the bottom rail and accumulated slat weight is to free fall.In many instances in the prior art, locking mechanisms are employed tolock the bottom rail, and the slats stacked thereon at a heightdetermined by the user. Pleated and other types of shades also include abottom rail and include similar raising, lowering and line member orcord locking mechanisms.

[0007] Spring motors have operating characteristics which findparticular utility in conjunction with assisting the elevating andlowering of a variable load such as that provided by venetian blind typewindow covering. Spring motors are well known in the art andconventionally comprise a flat ribbon of spring metal which ispre-stressed and coiled so as to have a natural or relaxed state inwhich the spring forms a tightly wound coil disposed on or in a springstorage or take up drum. The extended free end of the coil is attachedto the hub of an output or spring drive drum onto which the spring isbackwound by rotating the output drum in a direction to back or reversewind the spring thereon. When the load to which the output drum isconnected is released, the curling property of the spring causes it torewind onto or into the storage drum toward its natural or relaxedstate. Such spring motors as described above can be of constant orvariable force, depending upon the intended use of the motor. Thecharacteristics of a variable force spring motor can be obtained invarying ways, but varying the radius of curvature of the spring memberalong the length thereof is conventionally the preferred method.

[0008] In connection with the use of such a spring motor and a venetianblind, as an example, a control drum or spool is mounted co-axially withthe output drum for rotation therewith, and the flexible member or cordis wound onto the spool in a direction which provides for the unwindingof the cord to rotate the spring output drum in the direction forwinding the spring member thereon from the spring storage drum. When theforce necessary for such unwinding is relaxed, the spring member returnsto its naturally coiled position whereby the spring output drum isrotated by the spring member in a direction to rewind the cord or beltonto the spool. In those blinds with locking mechanism, such rewindingof the cord onto the control drum is inhibited.

[0009] When raising or lowering a load such as the bottom rail and slatsof a venetian blind, a pair of cords may be wound on the spool inopposite directions with the free ends of the cords attached adjacentthe opposite ends of the bottom rail. Such a system is shown in U.S.Pat. No. 5,531,257 issued on Jul. 2, 1996 to Newell Operating Company ofFreeport, Ill. When the bottom rail is lowered, the two cords unwindfrom the spool thus driving the spring output drum to wind the springmember thereon. Upward displacement of the bottom rail from a loweredposition results in the spring member rewinding on the spring storagedrum to rotate the spring output drum and thus the control drum in thedirection to rewind the two cords. In elevating and lowering a suspendedload of the foregoing example type, which is too heavy to provide desiredisplacement characteristics in connection with the upward and downwardmovement of the bottom rail, and using a single spring motor, many timesit is necessary to provide a larger spring motor or operate two or morespring motors in tandem.

[0010] When it is desired, the spring motor may be designed to allow thebalancing of the gravitational pull on the bottom rail and accumulatedslats and the resisting force of the spring motor so that the weight,even though increasing, as additional slats are accumulated on thebottom rail as it is raised, the bottom rail may be released and stay ata predetermined height. However, this is difficult under all conditions.

[0011] Because of the differences in materials of the slats, the size ofthe blind, the number of slats in the blind, the weight of these partsplus the weight of the bottom rail, etc. motors must have differentcharacteristics and be designed for different loads. It is difficult, ifnot impossible, to utilize the same motors on different types of theslatted blinds as well as shades or fabric covered blinds. The answer ofcourse, heretofore, has been blinds with lifting locks for the cords, orvarious other means of providing for a balanced blind system. In some,for example U.S. Pat. No. 5,531,257, issued on Jul. 2, 1996 to NewellOperating Company, Freeport Ill., utilize an electric motor to assistand to aid or facilitate the raising and lowering operations.

[0012] The motor of a type found in European Patent Application EP 0 796994 A2 published on Sep. 24, 1997, is illustrative of a spring motortypically employed in a venetian blind system. Each of such motors areof necessity designed with different specifications to account fordifferent loads due to different sizes, materials of the slats, and soforth.

SUMMARY OF THE INVENTION

[0013] The present invention features a cordless blind or shade in whicha spring motor is used to eliminate conventional pull cord and cord-lockmechanisms, and which is suitable for encountering a wide variety ofloads. This is accomplished in a weight suspension system including thespring motor for suspending a variable weight (e.g. the bottom rail andaccumulated slats of a blind) connected thereto at any of apredetermined but variable height. A drive actuator is connected to thespring motor to effect motion to the weight, and an adjustable frictionmember engageable with one of the spring motor and the drive actuatoradjustably alters the force necessary to effect motion of the weightconnected to the spring motor.

[0014] The present invention also features a system in which anadjustable friction member engageable with at least one of a coupleddrive and drive actuator for a spring motor allows for adjustment of theforce necessary to affect movement or motion of the coupled drive. Thisfeature allows for adjustment of the system friction (by adjustment ofthe adjustable friction member) so that a single spring motor design maybe employed for a variety of window blinds and shades of differingsizes, and having differing bottom rail weights, and materialcomposition. Of course a plurality of motors may be coupled in series soas to increase the spring force available for lifting heavier weightbottom rails and blind or slat material.

[0015] The manner in which the present invention accomplishes thesefeatures shall be described in the following detailed description of themost preferred embodiments, taken in conjunction with the figures whichillustrate both a typical blind system and a spring motor adapted forutilization in a wide variety of blind systems. Generally, the foregoingfeatures are accomplished in a blind or shade system by employing aconstant force or consistently variable force spring motor employing anadjustable friction member. The features are accomplished, in a blindsystem, which includes a headrail, a bottom rail and window coveringmaterial located therebetween. The bottom rail, as is conventional, ismoveable between a fully raised (or adjacent) and fully lowered (orremote) position with respect to the headrail and intermediate positionsas desired by the user. A spring motor is preferably located in theheadrail, which is, in use attached to the upper frame or exterior walllocated adjacent to a window. (While it is preferable to locate thespring motor in the headrail, it may also be positioned in the bottomrail but the additional weight of the spring motor must be taken intoaccount when the shade is being lifted, thus requiring a stronger springmotor to lift not only itself but accumulated slats or covering materialas the bottom rail is elevated and approaches the top rail).

[0016] As will be shown hereinafter, the spring motor includes a line orcord member receiving (storage) spool. At least a pair of line membersare coupled intermediate the bottom rail and the spool, the spring motoritself comprising a storage drum having a first axis and an output drummounted for rotation about a second axis parallel to and spaced from thefirst axis. A spring member is connected to and between the storage drumand the output drum thereby forming the springs motor. The headrailincludes laterally extending spaced apart side walls or drum supports onopposite sides of the drums to support them for rotation therebetween. Acoupled drive (gears) is connected to the storage and the output drum sothat rotation of one of the drums in a first direction about its axisaffects rotation of the other of the drums about its axis, but in anopposite direction, to cause winding and unwinding of the spring memberbetween the drums. A drive actuator which includes the spool, isconnected to the coupled drive to effect rotation of the drums, and anadjustable friction member is mounted for engagement with one of thecoupled drive and the drive actuator to adjustably alter the forcenecessary to affect movement of the coupled drive and the bottom rail byway of the line members. In this manner, when the load on the springmotor is at its highest, i.e., when the bottom rail and accumulatedslats are closely adjacent the top rail, the friction member may beadjusted so as to effectively support such a load. It is recognized thatthe accumulated weight, in conjunction with the adjustment to thefriction member, may also be adjusted, e.g. by altering the weight ofthe bottom rail. Such a scheme is disclosed in co-pending patentapplication Ser. No. 09/229,111, filed on Jan. 12, 1999 for “CellularLift Cord and Weight Adjustment Mechanism” to Voss et al. The end resultis that the blinds and/or shades of the system may be manipulated by theoperator or user to a balanced condition at a selected height by simplygrasping the bottom rail and urging it in an upward or downwarddirection.

[0017] Still other features of the present invention include thepossibility of adding friction enhancers, e.g. roughened or extrafriction material or by trimming the friction or adjusting it by addinglubricants and the like.

[0018] Another feature of the present invention is the method ofinsuring, the retention of the bottom rail relative to the headrail atany point between a first adjacent position and a second remote positionuntil a force is exerted sufficient to effect relative displacementtherebetween. The method comprises the steps of applying a frictionalforce to at least one of the flexible line, line storage spool andspring motor to effect retention of the bottom rail relative to saidheadrail at the point when the force is removed. More specifically thisis accomplished by insuring that the difference between the weight ofthe bottom rail plus slats or material, and the force applied to theweight is less than the frictional applied force.

[0019] Other features of the present invention will be described morecompletely in the following specification and claims taken inconjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic front elevational view, partially infragment to illustrate the placement of a spring motor for operation ina venetian blind;

[0021]FIG. 2 is an enlarged fragmentary plan view of the motor shown inFIG. 1;

[0022]FIG. 3 is an enlarged perspective view of an adjustable frictionmember which is engageable in the spring motor to permit adjustment ofthe friction so as to allow the motor to be employed with variousvenetian blind and/or shade systems;

[0023]FIG. 4 is a fragmentary view in plan of a drive actuator utilizingthe adjustable friction member illustrated in FIG. 3 to increase thefriction on the motor and thus the drive;

[0024]FIGS. 5 and 6 are another embodiment of an adjustable frictionmember that is also engageable with one of the coupled drive and driveactuators of the spring motor to adjustably alter the force necessary toaffect movement of the coupled drive and the bottom rail in the venetianblind/shade system;

[0025]FIG. 7 is a plan view of a drive actuator employing the adjustablefriction member illustrated in FIGS. 5 and 6;

[0026]FIG. 8 is a fragmentary, schematic view in plan of anotherembodiment of an adjustable friction member constructed in accordancewith the present invention;

[0027]FIG. 9 is an enlarged view of the dashed line portion of FIG. 8,illustrating the embodiment in greater detail;

[0028]FIG. 10 is a fragmentary, sectional view taken along line 10-10 ofFIG. 9;

[0029]FIG. 11 is a fragmentary, sectional view of another embodiment ofan adjustable friction member for use with the spool illustrated in FIG.8, and;

[0030]FIG. 12 is a fragmentary view in plan of an embodiment which maybe employed with any of the forgoing adjustable friction members but inwhich motors are coupled in series to accommodate even greater weightsdue to the blinds or slats and the bottom rail.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Referring now to the drawings, it is understood that the drawingsare intended for illustration of the preferred embodiments of theinvention and not for the purposes of limiting the invention. Asillustrated, FIG. 1 schematically portrays a motor 10 operativelyassociated with a venetian blind unit 12 to provide a cordlessarrangement for elevating and lowering the blind. As illustrated, thevenetian blind unit 12 includes a headrail 14, a bottom or bottom rail16, and a plurality of slats 18. As is known in the art, the slats 18are independently supported from the headrail 14 as by flexible membersor cords 20, 22 so as to be vertically spaced from one another when thebottom rail 16 is lowered, as shown in FIG. 1. The bottom rail 16 isconnected to the terminal ends 20 a, 20 b of the cords 20, 22. When thebottom rail is elevated, the slats collectively stack upon one anotherand are supported by the bottom rail 16 when the latter is elevated toits retracted position beneath and closely adjacent the headrail 14.Motor 10 may be mounted in the headrail by any convenient means.

[0032] Referring now to FIG. 2, the motor 10 comprises a storage drum 30having a first axis 30 a and an output drum 40 mounted for rotationabout a second axis 40 a parallel to and spaced from the first axis 30a. A spring member 35 is connected to and between the storage drum 30and the output drum 40 to form a spring motor 11. As illustrated, thespring motor 11 has or includes laterally extending, spaced apart drumsupports or side walls 50, 52 on opposite sides of the drums 30 and 40to support them for rotation therebetween. In the position shown in FIG.2, the spring 35 is tightly wound on the storage drum 30 (and thiscorresponds to a condition where, as will be shown hereinafter, thebottom rail 16 lies closely adjacent the top rail 14 supporting theslats 18 on the bottom rail). A coupled drive 60, in the presentinstance comprising a plurality of gears 62, 64, 66, and 68, have thegears 64 and 66 connected respectively to the storage drum 30 and theoutput drum 40 of the spring motor 11. The coupling of the drive by thegears forces rotation of one of the drums 30, 40 in a first directionabout its axis and the other of the drums in an opposite directionallowing winding and unwinding of the spring member 35 between thedrums.

[0033] The coupled drive actuator comprises flexible member or cordstorage spools 70 and 72, and are connected to the gears 62 and 68respectively while being mounted for rotation by axles 71 and 73 of thespools 70 and 72. As shown, the flexible member or cord 22 is wound uponspool 72 while the flexible cord 20 is wound on the spool 70. Becausethe gears 62 and 68 form part of the coupled drive or drive train 60, itis easy to ascertain that if the cord 22 (relative to FIG. 2) is movingto the right, in the direction of arrow 21, then the cord 20 must bemoving to the left in the direction of the arrow 19. This corresponds toa lowering of the blind. Again because of the coupled drive and coupleddrive actuator 60, as the flexible member or cord 22 is pulled to theright, the spring member 35 starts winding on the output drum 40 andunwinding from the storage drum 30.

[0034] In order to permit adjustment of the motor so as to accommodatevarying loads, i.e., different size blinds or shades and differentdensity materials, an adjustable friction member is provided forengagement with one of the coupled drive 60 and the drive actuator (orboth, if desired) to adjustably alter the force necessary to affectmovement of the coupled drive 60. To this end, and as best illustratedin FIG. 3, an adjustable friction member 80, for example, a bifurcatedspring or shim like member 81, having spaced apart, outwardly curved orbowed legs 82 and 83 which define a slot 84 therebetween, is easilyinserted intermediate the drum support or side wall 52 and one end 75 ofthe spool 72 (see FIG. 4). As shown, the slot 84 is dimensioned to allowclearance room between the shaft or axle 73 upon which the spool 72 ismounted for rotation. In this manner, the bowed legs 82 and 83 bearagainst the end 75 of the spool 72 and against the interior of the drumsupport or side wall 52. To permit the adjustable friction member 80 tobe properly seated in the position as illustrated in FIG. 4, the memberis provided with a lip like extension 85 which may be seated upon theedge 52 a of the side wall or drum support 52. With the shim likeconstruction of the adjustable friction member 80, the operator, whenadjusting the motor for its intended load, may bend the legs 82, 83 ofthe shim so as to increase or decrease the pressure or frictionalengagement between the shim 81 and the end 75 of the spool 72. In thismanner, differing load force requirements may be accommodated quickly,inexpensively and with ease when the venetian blind or shade is beingconstructed.

[0035] Another embodiment of an adjustable friction member 90,constructed in accordance with the present invention, is illustrated inFIGS. 5-7. In this embodiment, an adjustable cord drag mechanism isutilized to adjust the cord friction. To this end and as illustrated, inFIG. 5, a biased arm or elongated bar 92, has an aperture and the like93 at an enlarged bottom end and another aperture 94 a for journaling ashaft 94 and the like upon which a spool 95 is mounted for rotation. Aspring 96 is connected along the bar and biases, when abutting surface,such as the interior bottom of the top rail 14, to bias the bar 92 in acounterclockwise direction about the pivot aperture 93. As bestillustrated in FIG. 7, the bar 92 is pivoted for rotation about a pivotpin 97 which allows the bar to pivot counterclockwise about the pin 97when the bar is connected by the pin to one of the drum supports or sidewalls, for example and as shown in FIG. 7 the side wall 52. In theillustrated instance, the cord 22 passes over the spool 95, adding tothe friction of the system. As may be ascertained from FIG. 7 as thetension on the cord 22 increases, the spring 96 will undergo compressioncausing the arm 90 or bar 92 to pivot about shaft 97 into a depressedcondition. As the bottom rail is raised, and tension is decreased on theline cord 22, the bar will rotate counterclockwise about the pivot 93,decreasing the tension and the friction in the system. Thus theadjustable friction member 90 is dynamic in operation as opposed to thestatic operation of the shim 81.

[0036] It should be recognized that a mirror image of the arm of FIG. 5may also be provided for operation in conjunction with the cord 20 onthe spool 70 (see FIG. 2) by merely attaching the adjustable frictionmember 90 a and biased bar 92 a to one of the side walls or drumsupports 50, 52. The accompanying spool 95 a and axle 94 b permitrotation of the spool 95 a when the cord 20 is moving so as to unwind orwind cord 20 on and off the spool 70. In the preferred mode of thisparticular embodiment, it may be preferable to have both adjustablefriction members 90 and 90 a mounted to form a more balanced system,although the system will work with one or the other of the biased armsmounted on either of the drum supports or side walls 50, 52.

[0037] In still another embodiment of the adjustable friction member anadjustable drag mechanism is employed for altering the force necessaryfor rotation of drums. Turning now to the embodiments illustrated inFIGS. 8-11, a radially adjustable core member permits adjustment of thefriction opposing the rotation of, for example a spool or gear. As shownin FIGS. 2 and 7, and only by way of example, the axle 73, associatedwith spool 72, may be secured to the spool 72 and gear 50. By replacingthe axle 73 with a tube 100, connected to the spool 72, and connectingthe spool to the gear 68, a friction member may be placed interiorly ofthe tube. The adjustable friction member may take a variety of forms,such as illustrated best in FIGS. 8-10, and includes an insert 112 forplacement interiorly of the tube 100. The insert 112 includes a bottomportion 114 and axially and longitudinally tapered legs 116. Coaxiallyof the bottom 114 and of the legs 116 is an aperture 118 adapted toreceive a screw member 120, best illustrated in the cross section ofFIG. 9. As the screw moves into the insert 112, the tapered legs 116tend to radially spread so as to engage the interior surface 101 of thetube 100 thereby increasing the rotational friction tending to inhibitrotation of the spool 72, even when the force exerted on the cord 22,tending to displace or affect rotation of the spool, is increased dueto, for example, an increase in the weight applied to the bottom rail.

[0038] In yet another embodiment of an adjustable friction member, aradially adjustable core member includes, and as illustrated in FIG. 11,a cylindrical insert 135 having an upper portion 125 and a spaced apartmoveable or distal end portion 130 is connected as by a rubber or otherexpansible material cylinder 135 supporting the upper and distal endportions, 125 and 130 respectively.

[0039] A screw member 140 has a shank 142, and a threaded end portion144, the screw portion engageable with a threaded nut like portion 132in the distal end portion 130 of the insert. As shown in FIG. 11, as thescrew is rotated in a first direction, the distal end 130 is pulledtowards the upper or head portion 125 as in the direction of the arrow133, causing the rubber cylinder 135 to expand (as shown in dashed lines135 a) into engagement with the interior of the tube 100. In thismanner, the friction may be increased or decreased and adjusteddependent upon the force on the system or the cord 22. As may be readilyunderstood, the inserts provided in FIGS. 8-11 may also be utilized withspool 70. Moreover, it should be understood that other inserts or othermeans of grasping, for example the axle 73 so as to allow for adjustmentof the friction in the system may easily be employed to permit a numberof different slats or blind arrangements to be used with a single springmotor.

[0040] It should also be recognized that since the force exerted by thespring motor should be able to support the load of the bottom rail andaccumulated slats, with large loads (wide, heavy blinds) it may bedesirable to couple motors together to increase the available springforce. To this end, a coupling scheme, such as shown and applied in“Cordless, Balanced venetian Blind or Shade With Consistent VariableForce Spring Motor” Ser. No. 08/223,989, Filed Apr. 6, 1994; now U.S.Pat. No. 5,482,100, issued Jan. 9, 1996, and herein incorporated byreference, may be employed, and is illustrated in FIG. 12.

[0041] Referring now to FIG. 12, an identical spring motor 11 b is showncoupled to the motor 11, heretofore described. As shown, the springmotor 11 b comprises a storage drum 30 b having a first axis 30 c and anoutput drum 40 b mounted for rotation about a second axis 40 c parallelto and spaced from the first axis 30 c. A spring member 35 b isconnected to and between the storage drum 30 b and the output drum 40 bto form the spring motor 11 b. As illustrated, the spring motor 11 b,like the spring motor 11, includes the laterally extending, spaced apartdrum supports or side walls 50, 52 on opposite sides of the drums 30 band 40 b to support them for rotation therebetween. In the positionshown in FIG. 12, the spring 35 b is tightly wound on the storage drum30 b (and this corresponds to a condition the bottom rail 16 liesclosely adjacent the top rail 14 supporting the slats 18 on the bottomrail). A coupled drive 60, in the present instance comprising aplurality of gears 62, 64 b, 66 b, 64, 66, and 68, have the gears 64 band 66 b connected respectively to the storage drum 30 b and the outputdrum 40 b of the spring motor 11 b. The coupling of the drive by thegears forces rotation of one of the drums 30 b, 40 b in a firstdirection about its axis and the other of the drums in an oppositedirection allowing winding and unwinding of the spring member 35 bbetween the drums.

[0042] Similar to the embodiment shown in FIG. 2, the coupled driveactuator 60 comprises flexible member or cord storage spools 70 and 72,and are connected to the gears 62 and 68 respectively while beingmounted for rotation by axles 71 and 73 of the spools 70 and 72. Asshown, the flexible member or cord 22 is wound upon spool 72 while theflexible cord 20 is wound on the spool 70. Because the gears 62 and 68form part of the coupled drive or drive train 60, it is easy toascertain that if the cord 22 (relative to FIG. 12) is moving to theright, then the cord 20 must be moving to the left. This corresponds toa lowering of the blind. Again because of the coupled drive and coupleddrive actuator 60, as the flexible member or cord 22 is pulled to theright, the spring members 35 and 35 b starts winding on the output drums40 and 40 c respectively, and unwinding from the storage drums 30 and 30b. It should be recognized that the adjustable friction devices ormembers disclosed heretofore, may also be applied to the structure ofFIG. 12.

[0043] Of course it should also be recognized that there are numerousother ways to effect or alter the friction in a system, for example, alubricant could be added between fixed and moveable parts. For example,a lubricant could be applied to the adjustable legs 82, 83 of theadjustable friction member 80 to decrease the friction of the legsagainst the end 75 of the spool 72 (see FIGS. 2-4). Alternatively, thewidth of the legs 82, 83 could be decreased (or increased for thatmatter) or made of different materials to decrease or increase thefriction between the end 75 of the spool 72 and the adjustable frictionmember 80. Alternatively, the cords 20, 22 may be formed with alubricant, e.g. a wax or the like to change the friction of the coupleddrive actuator. By way of another example, consider the embodiment ofFIGS. 5-7, the ability of the spools 95, 95 a to rotate may be inhibitedto increase the friction against the cords 22, 20. Alternatively, thecords or spools may be lubricated to decrease the friction. Moreover,rubbing or rolling surfaces may be roughened or applied with otherfriction enhancing material, e.g., embedded grit or sand, to allow foran increase in friction.

[0044] It is also recognized that inasmuch as the blind constructiondetermines the weight encountered by the spring motor, the addition orremoval of weight to the bottom rail 16 will change the amount offriction necessary in the system to achieve balance. Thus a combinationof weight/friction adjustment, relative to the available spring force ofthe motor, will allow for proper balancing of the blind. This followsthe fundamental equation, in this kind of blind system, where thefrictional force must exceed the absolute value of the weight (bottomrail plus accumulated slats, if any, plus any other weight supported bythe line cords) minus the spring force applied by the spring motor. Ofcourse, as indicated above, the spring force may also be varied, byapplying two or more coupled motors to accommodate an increase in weightand in order to achieve the desired balance while maintaining the forceof friction the same.

[0045] The following equation sets forth the relationship betweenfriction, load and spring force.

f>|ΣW−Sf|

[0046] Where f=Frictional Force

[0047] ΣW=weight of bottom rail plus accumulated slats, plus any othersupported weight at height of balance.

[0048] Sf=force of the spring motor

[0049] Thus the present invention features a cordless blind or shade inwhich a spring motor is used to eliminate conventional pull cord andcord lock mechanism and which is suitable for encountering a widevariety of loads making it unnecessary to design a specific motor for aspecific end use. As shown, the system allows for an adjustable frictionmember engageable with one of a coupled drive and drive actuator for aspring motor so as to permit adjustment of the force necessary to affectmovement of motion of the coupled drive. In this manner, adjustment ofthe adjustable friction member so that a single spring motor design (andunder heavy loads or severe conditions even a coupled pair of springmotors) may be employed for a variety of uses such as window blinds andshades of differing sizes, weights and material composition, isfacilitated.

What is claimed is:
 1. A motor comprising a storage drum having a firstaxis, an output drum mounted for rotation about a second axis parallelto and spaced from said first axis; a spring member connected to andbetween the storage drum and the output drum to form a spring motor,said spring motor having laterally extending, spaced apart drum supportson opposite sides of said drums to support them for rotationtherebetween; a coupled drive connected to said storage and output drumwhereby rotation of one of said drums in a first direction about itsaxis effects rotation of said other of said drums about its axis and inan opposite direction to cause winding and unwinding of said springmember between said drums; a drive actuator connected to said coupleddrive to effect rotation of said drums, and an adjustable frictionmember engageable with one of said coupled drive and said drive actuatorto adjustably alter the force necessary to effect movement of saidcoupled drive.
 2. A motor in accordance with claim 1 wherein saidadjustable friction member comprises a flexible and resilient springlike member mounted between said drum support and said drive actuator tofrictionally engage said drive actuator, at least upon rotation thereof,and configured to allow for adjustment of the force necessary to effectrotation of said coupled drive.
 3. A motor in accordance with claim 2wherein said spring like member is formed of a bifurcated member havingspaced apart and adjustably bowed legs for altering the pressure betweensaid drum support and said drive actuator.
 4. A motor in accordance withclaim 1 including a spool connected to and forming part of said driveactuator; and a flexible line member for attachment to and winding uponsaid spool for accommodating a weight thereon on at least a portion ofsaid line member extending from said portion thereof wound upon saidspool, said spring motor and said friction member configured to suspenda weight, attached to said line member, at any of a predeterminedheight.
 5. A motor in accordance with claim 4 wherein said adjustablefriction member comprises a flexible and resilient spring like membermounted between said drum support and said drive actuator tofrictionally engage said drive actuator, at least upon rotation thereof,and configured to allow for adjustment of the force necessary to effectrotation of said coupled drive.
 6. A motor in accordance with claim 5wherein said spring like member is formed of a bifurcated member havingspaced apart and adjustably bowed legs for altering the pressure betweensaid drum support and said drive actuator.
 7. A motor in accordance withclaim 4 wherein said spool includes an axis which is parallel to andspaced from both said first and second axis and supported by said drumsupports; and said coupled drive includes a gear train with a first gearconnected to said storage drum to effect rotation thereto and a secondgear, engageable by said first gear and connected to said output drum,and a third gear connected to said spool and engageable with one of saidfirst and second gears.
 8. A motor in accordance with claim 7 whereinsaid adjustable friction member comprises a flexible and resilientspring like member mounted between said drum support and said driveactuator to frictionally engage said drive actuator, at least uponrotation thereof, and configured to allow for adjustment of the forcenecessary to effect rotation of said coupled drive.
 9. A motor inaccordance with claim 8 wherein said spring like member is formed of abifurcated member having spaced apart and adjustably bowed legs foraltering the pressure between said drum support and said drive actuator.10. A motor in accordance with claim 7 including a second spool havingan axis parallel to and spaced from both said first and second axis andsupported by said drum supports; said second spool connected to andforming part of said drive actuator, and a fourth gear connected to oneof said gears such that rotation of said first spool in a firstdirection effects rotation of said second spool in an oppositedirection.
 11. A motor in accordance with claim 10 wherein saidadjustable friction member comprises a flexible and resilient springlike member mounted between said drum support and said drive actuator tofrictionally engage said drive actuator, at least upon rotation thereof,and configured to allow for adjustment of the force necessary to effectrotation of said coupled drive.
 12. A motor in accordance with claim 11wherein said spring like member is formed of a bifurcated member havingspaced apart and adjustably bowed legs for altering the pressure betweensaid drum support and said drive actuator.
 13. A motor in accordancewith claim 10 including another flexible line member for attachment toand winding upon said second spool for accommodating a weight thereon onat least a portion of said line member extending from said portionthereof wound upon said spool, said spring motor and said frictionmember configured to suspend a weight, attached to said another linemember, at any of a predetermined height.
 14. A motor in accordance withclaim 13 wherein said adjustable friction member comprises a flexibleand resilient spring like member mounted between said drum support andsaid drive actuator to frictionally engage said drive actuator, at leastupon rotation thereof, and configured to allow for adjustment of theforce necessary to effect rotation of said coupled drive.
 15. A motor inaccordance with claim 14 wherein said spring like member is formed of abifurcated member having spaced apart and adjustably bowed legs foraltering the pressure between said drum support and said drive actuator.16. A motor in accordance with claim 4 wherein said adjustable frictionmember includes an adjustable drag mechanism for altering the rotationof said drums.
 17. A motor in accordance with claim 16 wherein saidadjustable drag mechanism comprises a spool, a spring biasing said spoolto support said flexible line member to effect altering of the tensionand thus the friction in said line.
 18. A motor in accordance with claim16 wherein said adjustable drag mechanism includes a radially adjustablecore member for altering the rotational friction of at least one of saiddrive actuator and said drive.
 19. A window covering of the typeincluding a headrail, a bottom rail and window covering material locatedtherebetween, the bottom rail being moveable between a fully raised andfully lowered position with respect to the headrail and intermediatepositions, comprising in combination: a spring motor attached to saidheadrail and including a line member receiving spool; at least a pair ofline members coupled intermediate the bottom rail and the spool; saidspring motor comprising a storage drum having a first axis, an outputdrum mounted for rotation about a second axis parallel to and spacedfrom said first axis; a spring member connected to and between thestorage drum and the output drum thereby forming said spring motor, saidheadrail including laterally extending, spaced apart side walls onopposite sides of said drums to support them for rotation therebetween;a coupled drive connected to said storage and output drum wherebyrotation of one of said drums in a first direction about its axiseffects rotation of said other of said drums about its axis and in anopposite direction to cause winding and unwinding of said spring memberbetween said drums; a drive actuator, including said spool, connected tosaid coupled drive to effect rotation of said drums, and an adjustablefriction member engageable with one of said coupled drive and said driveactuator to adjustably alter the force necessary to effect movement ofsaid coupled drive and said bottom rail by way of said line members. 20.A window covering in accordance with claim 19 wherein said adjustablefriction member comprises a flexible and resilient spring like membermounted between said drum support and said drive actuator tofrictionally engage said drive actuator, at least upon rotation thereof,and configured to allow for adjustment of the force necessary to effectrotation of said coupled drive.
 21. A motor in accordance with claim 20wherein said spring like member is formed of a bifurcated member havingspaced apart and adjustably bowed legs for altering the pressure betweensaid drum support and said drive actuator.
 22. A window covering inaccordance with claim 19 wherein said spring motor and said frictionmember are configured to suspend the bottom rail, attached to said linemembers, at any of a predetermined height.
 23. A motor in accordancewith claim 22 wherein said adjustable friction member comprises aflexible and resilient spring like member mounted between said drumsupport and said drive actuator to frictionally engage said driveactuator, at least upon rotation thereof, and configured to allow foradjustment of the force necessary to effect rotation of said coupleddrive.
 24. A motor in accordance with claim 23 wherein said spring likemember is formed of a bifurcated member having spaced apart andadjustably bowed legs for altering the pressure between said drumsupport and said drive actuator.
 25. A window covering in accordancewith claim 22 wherein said spool includes an axis which is parallel toand spaced from both said first and second axis and supported by saidside rails; and said coupled drive includes a gear train with a firstgear connected to said storage drum to effect rotation thereto and asecond gear, engageable by said first gear and connected to said outputdrum, and a third gear connected to said spool and engageable with oneof said first and second gears.
 26. A window covering in accordance withclaim 25 including a second spool having an axis parallel to and spacedfrom both said first and second axis and supported by said side rails;said second spool connected to and forming part of said drive actuator,and a fourth gear connected to said second spool and one of said othergears such that rotation of said first spool in a first directioneffects rotation of said second spool in an opposite direction.
 27. Awindow covering in accordance with claim 26 wherein said flexible linemembers are attached to and wound upon said first and second spools foraccommodating the weight of said bottom rail and window coveringmaterial intermediate said headrail and said bottom rail, said springmotor and said friction member configured to suspend said bottom railand covering material at any predetermined height.
 28. A window coveringin accordance with claim 27 wherein said adjustable friction memberincludes an adjustable drag mechanism for altering the rotation of saiddrums.
 29. A window covering in accordance with claim 28 wherein saidadjustable drag mechanism comprises a spool, a spring biasing said spoolto support said flexible line member to effect altering of the tensionand thus the friction in said line.
 30. A window covering in accordancewith claim 29 wherein said adjustable drag mechanism includes a radiallyadjustable core member for altering the rotational friction of at leastone of said drive actuator and said drive.
 31. A window covering inaccordance with claim 27 including a lubricant on said flexible line todecrease friction in said line.
 32. A window covering in accordance withclaim 19 including an application to one of a rubbing or a rollingsurface of friction enhancing material, to allow for an alteration inthe friction between such surfaces.
 33. A weight suspension systemincluding a spring motor for suspending a variable weight connectedthereto at any of a predetermined but variable height; a drive actuatorconnected to said spring motor to effect motion to said weight, and anadjustable friction member engageable with one of said spring motor andsaid drive actuator to adjustably alter the force necessary to effectmotion of said weight connected to said spring motor.
 34. A weightsuspension system in accordance with claim 33 wherein said adjustablefriction member comprises a flexible shim member.
 35. A weightsuspension system in accordance with claim 33 wherein said spring motorcomprises a spring member mounted for translation between first andsecond spring member drums; and a drive coupling said drums forcounter-rotation.
 36. A weight suspension system in accordance withclaim 35 wherein said drive actuator is couple to at least one of saidspring member drums.
 37. A weight suspension system in accordance withclaim 36 wherein said adjustable friction member comprises an adjustabledrag mechanism engageable with one of said spring member drums and saiddrive actuator for altering the force necessary to effect rotation ofsaid drums.
 38. A window covering of the type including a headrail, abottom rail and window covering material located therebetween, thebottom rail being moveable between a fully raised and fully loweredposition with respect to the headrail and intermediate positions,comprising in combination: a spring motor attached to one of saidheadrail and bottom rail and including a flexible line storage spoolwith flexible line spooled thereon and connected to the other of saidheadrail and bottom rail; and an adjustable friction member engageablewith one of said spring motor, line storage spool and said flexible lineto adjustably alter the force necessary to effect movement of saidbottom rail towards and away from said headrail by way of said linemember.
 39. A window covering in accordance with claim 38 wherein saidadjustable friction member comprises a flexible and resilient springlike member mounted to frictionally engage said storage spool, andconfigured to allow for adjustment of the force necessary to effectrotation of said coupled drive
 40. A window covering in accordance withclaim 38 wherein said adjustable friction member comprises theapplication of a lubricant.
 41. A window covering in accordance withclaim 38 wherein said adjustable friction member comprises anapplication of a friction enhancing material.
 42. A window covering inaccordance with claim 38 including a plurality of spring motors mountedserially in one of said bottom and headrail.
 43. In a window blindsystem having a headrail and a bottom rail with window covering locatedtherebetween, and a spring motor adjustably positioned in one of saidhead or bottom rails including a flexible line storage spool withflexible line spooled thereon and connected to the other of saidheadrail and bottom rail to permit separation of said bottom rail fromsaid headrail between a first position with the headrail adjacent thebottom rail, and in a second position with the headrail remotelypositioned relative to the bottom rail; a method of insuring, theretention of the bottom rail relative to the headrail at any pointbetween said first and second positions until a force is exertedsufficient to effect relative displacement therebetween; the methodcomprising the steps of: applying a frictional force to at least one ofsaid flexible line, line storage spool and spring motor to effectretention of the bottom rail relative to said headrail at said pointwhen said force is removed.
 44. In a window blind system in accordancewith claim 43 including the step of adjusting the frictional force toexceed the absolute value of the weight placed on said flexible lineless the force exerted on the line by the spring motor.
 45. In a windowblind system in accordance with claim 43 including the step of adjustingthe weight on said line so that the difference between the weight andthe force exerted on said line by said spring motor is less than theapplied frictional force.
 46. In a window blind system in accordancewith claim 44 including the step of adding a second spring motor inseries with said spring motor to increase the spring force to decreasethe difference between the absolute value of the weight placed on saidflexible line less the force exerted on the line by the series connectedspring motors.